The present invention relates to particle separators and debris control systems for use with gas turbine engines.
Rotorcraft (e.g., helicopters) that use gas turbine engines can operate at a variety of altitudes, and can generally operate at relatively lower altitudes than most fixed-wing aircraft. Low-altitude operation poses operational difficulties for gas turbine engines not always presented at higher altitudes. For instance, landing and taking-off from unpaved areas can “kick up” large amounts of dust and debris. As such, gas turbine engines of rotorcraft operating at low altitudes are often exposed to ambient air that contains a significant amount of debris, typically consisting of large amounts of small, airborne particles or dust. Debris ingested by gas turbine engines is problematic, and can cause erosion and other damage to components of the engine. Such damage can cause engine performance to deteriorate, and can make engine repairs necessary. For example. gas turbine engines contain airfoils having thin edges and tips that are highly sensitive to erosion, and any erosion damage to those areas can significantly impair the efficiency and effectiveness of the airfoil.
Inlet particle separator (IPS) systems are known that provide fine object filtering of ambient air that enters gas turbine engines. The IPS system typically includes a specially designed duct or a ramp-like structure hereinafter referred to as a “ramp” that propels particles radially outward while allowing only relatively clean air to pass through a more radially inward passageway to the interior of the engine. These known IPS systems can include blowers to help move ambient air along the “ramp” to a collector and then expel particles from the engine. Those blowers are mechanically powered by a fixed-gear connection to a gas turbine engine spool. A problem with these systems is that the mechanical power diverted to the IPS system produces a parasitic power loss that negatively impacts fuel burn efficiency of the engine. This is at least partially due to the fact that fixed gearing powers the blower at a constant speed (that is, a speed that is a constant proportion of engine operational speed) whenever the engine is operating, without the capability to turn the blower off while the gas turbine engine is still operating. This is inefficient because in certain situations, such as when the gas turbine engine is operating at relatively high altitudes, the amount of debris in ambient air is generally relatively low. In those situations where the amount of debris is low, operation the IPS system blower provides little or no practical benefit, yet still produces a parasitic power loss. Moreover, the amount of debris in ambient air is dynamically variable across engine operation cycles, but known engine systems do not provide a means to adaptively match debris control system operation to actual ambient air conditions in real time.